Kestrel permission denied for non-root user
It works for me if the port is higher then 80. You need to run Kestrel on a different port within the code itself, maybe check the json files.
There might be running previous instance of your app in the server. Try running netstat -tulpn | grep LISTEN to see which PID is using the port(s) and kill it if necessary
In my case the ASPNETCORE_URLS setting in environment variables or appsettings.json was set to http://+:80.
Changing it to http://+:5000 worked. Make sure you change your Docker port bindings as well, or load balancer settings if using AWS.